Abstract

Memory interleaving includes providing a non-power of two number of channels in a computing system and interleaving memory access among the channels.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of and claims the benefit of priority to U.S. patent application Ser. No. 10/340,220, filed Jan. 10, 2003, now U.S. Pat. No. 6,941,438; the disclosure of the prior application is considered part of (and is incorporated by reference in) the disclosure of this application.

BACKGROUND

A channel generally refers to a pathway between a computer system and other computing systems and/or other devices. Each of a computing system's channels is an independent unit that can transfer data at the same time as other channels. Each channel is typically assigned a segment of memory address space and can transfer data corresponding to its assigned memory address space. In this way, the computing system's processor may access different segments of memory via different channels without idling while the memory completes an access to one segment before beginning another memory access. This type of memory access is generally called interleaving.

DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of an example channel control system.

FIG. 2 is a flowchart of an example process of memory interleaving.

FIG. 3 is a flowchart of an example process of determining whether a region is within a channel.

FIG. 4 is a flowchart of an example process of reducing an address.

FIG. 5 is a block diagram of an example address reduction.

FIG. 6 is a flowchart of an example process of adjusting an address.

FIG. 7 is a flowchart of an example process of address remapping.

FIG. 8 is a block diagram of an example machine system.

DESCRIPTION

Referring to FIG. 1, an example channel control system 100 can interleave access to a memory using channel controllers 102(1)-102(X) each associated with one channel. X can equal any positive whole number greater than one, including non-power of two positive whole numbers (three, five, six, etc.). Whatever the value of X, interleaving may be performed without using one or more bits of a memory address to indicate which channel to use in accessing the memory. Because no address bits need to be used in channel selection, the number of channels for interleaving is not restricted to a power of two number of channels as in traditional channel interleaving. Addresses may be mapped to the channel controllers 102(1)-102(X), and accesses to the memory may be concurrently made for addresses mapped to different channels.

Each of the channel controllers 102(1)-102(X) includes one of X match detect mechanisms 104(1)-104(X) and one of X address and count remapping mechanisms 106(1)-106(X). Each of the channel controllers 102(1)-102(X) receives information regarding a region to access in a memory and determines whether its associated channel is mapped to access data included in that region. The channel controllers 102(1)-102(X) typically make their determinations in parallel although they could process the information according to some pre-programmed priority or ordering scheme.

The information received by the channel controllers 102(1)-102(X) can include a data pair including a start address indicating where to begin accessing data in the memory and a count indicating how much data to access starting at the start address. The count is typically provided in bytes although any data measurement or size indicator may be used. The start address and the count define a region beginning at the start address and extending for a number of bytes indicated by the count (or as otherwise indicated by the count depending on how the count is provided).

Each of the match detect mechanisms 104(1)-104(X) determines if its associated channel is mapped to any of the addresses included in the region. Addresses may be mapped to the channels using a traditional scheme that assigned segments of address space to channels and/or using a scheme described further below that can spread adjacent addresses over the channels such that adjacent or nearby addresses may be spread over multiple channels. The channel may be mapped to access no addresses included in the region, all addresses included in the region, or some of the addresses included in the region. If a channel is mapped to some of the addresses included in the region, then part of the region lies within the channel and at least two channels are mapped to that region and may both access the region.

If one of the match detect mechanism 104(1)-104(X) determines that part of the region lies within its associated channel, then the one of the address and count remapping mechanisms 106(1)-106(X) associated with that channel determines a remapped start address and a remapped count indicating a part of the access for its associated one of the channel controllers 102(1)-102(X) to complete. The address and count remapping mechanisms 106(1)-106(X) may determine remapped addresses and remapped counts while the match detect mechanisms 104(1)-104(X) determine which channel or channels (if any) map to the region to save on processing time.

Once the channel controllers 102(1)-102(X) have determined if their associated channels map to the region, the appropriate one or ones of the channels may access the data in indicated region. In this way, addresses may be mapped to channels such that multiple channels may be used to access data at relatively close addresses. Furthermore, an interleave scheme can include using two or more channels, including a non-power of two number of channels.

In other examples, the match detect mechanisms 104(1)-104(X) and/or the address and count remapping mechanisms 106(1)-106(X) may be external to the channel controllers 102(1)-102(X). Furthermore, some or all of the channel controllers 102(1)-102(X) may use the same one or ones of the match detect mechanisms 104(1)-104(X) and/or the address and count remapping mechanisms 106(1)-106(X).

FIG. 2 shows an example process 200 of memory interleaving. In the process 200, the channel controller 102 receives 202 address and count information about a region to access in memory. (Each of the channel controllers 102(1)-102(X) receives the same information.)

The channel controllers 102(1)-102(X), the match detect mechanisms 104(1)-104(X), and the address and count remapping mechanisms 106(1)-106(X) each function similar to their like-named counterparts. For simplicity, the match detect mechanism 104(1) (“match detect 104”) and the address and count remapping mechanism 106(1) (“remap 106”) included in the channel controller 102(1) (“channel controller 102”) are used as representative examples.

The match detect 104 determines 204 how much of the region lies with the channel associated with the channel controller 102, channel one in this example. An example of how the match detect 104 may make such a determination is discussed further below.

If none of the region lies within the channel, then the process 200 ends 206 because the data to be accessed cannot be accessed through that channel.

If the region lies entirely within the channel, then the channel controller 102 triggers 208 an access of an amount of data equal to the count starting at the start address through the channel. The channel controller 102 may itself retrieve the data.

If the region lies partially within the channel, then the remap 106 adjusts 210 the address and the count to an adjusted address and adjusted count so that the channel only accesses data in its assigned region. The channel controller 102 may then trigger 212 an access of an amount of data equal to the adjusted count starting at the adjusted start address through the channel. The channel controller 102 may itself retrieve the data. For example, the start address may be indexed within one channel but the count extends the region into an area mapped to another channel, and the other channel needs to adjust the start address to reflect where the region begins in its indexed area. The adjusted start address may be the same as the start address while the adjusted count differs from the count in the case where the count extends beyond a channel's mapped area.

FIG. 3 shows an example determination process 300 of how the match detect 104 may determine whether and how much of a region lies within a channel. In the determination process 300, the match detect 104 calculates 302 an upper address of the region corresponding to the end of the data included in the region. The match detect 104 may calculate the upper address as the start address plus the count minus one. The one is subtracted to account for the data at the start address.

The match detect 104 reduces 304 the upper address and the start address to two bits each. With the addresses reduced to two bits each, the match detect 104 can determine if the region lies at least partially within the channel associated with the match detect. The addresses may be reduced to two bits each because in an example including three channels (X equals three), each of the channels can be represented by a different two bit combination (e.g., “01” for channel one, “10” for channel two, and “11” for channel three) and the two bit representation of the channel including the address can be used in reducing the address to help determine whether the channel associated with the match detect 104 is mapped to the region. If the system includes more than three channels, the addresses may be reduced to more than two bits because more than two bits may be necessary to represent each of the different channels. An example of how the match detect 104 may perform a reduction is discussed further below.

The match detect 104 determines 306 if the channel number associated with the match detect 104 (one in this example) matches either the reduced upper address or the reduced start address. If not, then none of the region lies within the channel.

If either reduced address matches the channel number, then the match detect 104 determines 308 if both the reduced upper address and the reduced start address match the channel number. If so, then the entire region lies within the channel. If not, then only one of the reduced addresses matches the channel number and only part of the region lies within the channel. The match detect 104 determines 310 if the reduced start address matches the channel number. If so, then a lower part of the data transfer (access), a part starting at the start address, lies within the channel. If not, then the match detect 104 concludes that an upper part of the data transfer, a part starting at an address higher than the start address and continuing through the upper address (unless the starting address of the upper part is the upper address in which case the upper part of the data transfer includes only the upper address), lies within the channel. The match detect 104 in this example checks for a match with the start address and makes an assumption about an upper address match based on that determination, but the match detect 104 may check the upper address and make an assumption about the start address in other examples.

FIG. 4 shows an example reduction process 400 that the match detect 104 may use to reduce an address. In the reduction process 400 generally, as shown in an example address reduction 500 in FIG. 5, the match detect 104 takes five levels of gating to reduce a thirty-one bit address 502 to a two bit output number 504. The match detect 104 may ignore one or more bits included in the address 502 that are not part of the start or upper address. In this example showing a start address, the match detect 104 ignores the seven bits included in the address that represent a byte offset (the interleave byte size) and considers the twenty-four bit start address. One of the gating levels takes as an input a channel number 506 of the channel that holds the address.

Referring back to FIG. 4, the match detect 104 recodes 402 the address using 2-bit to 2-bit recoding to produce a first number of bits including as many bits as the address (twenty-four bits) according to the following table:

Input

Output

n + 1

n

2

1

0

0

0

0

0

1

0

1

1

0

1

0

1

1

0

0

The match detect 104 reduces 404 the first number of bits using a 4-bit to 2-bit reducer to produce a second number of bits including the half as many bits as the first number of bits (twenty-four bits reduced to twelve bits) according to the following table:

00

01

10

00

00

01

10

(0)

(1)

(2)

01

01

10

00

(1)

(2)

(0)

10

10

00

01

(2)

(0)

(1)

The match detect 104 reduces 406 the second number of bits according to the above 4-bit to 2-bit reducer table to produce a third number of bits including half as many bits as the second number of bits (twelve bits reduced to six bits).

The match detect 104 reduces 408 the third number of bits plus the channel number including the address according to the above 4-bit to 2-bit reducer table to produce a fourth number of bits (eight bits reduced to four bits). If the match detect 104 did not include the channel number as an input in this reduction, there would be two unused inputs. The match detect 104 may receive the channel number from the remap 106, may look it up in an address mapping table that indexes addresses and their corresponding channel numbers, or may otherwise acquire the channel number.

The match detect 104 adds 410 the two resulting 2-bit recoded numbers. Sums of zero, one, and two do not change while a sum of four adds to zero. This addition produces the final two-bit output of the reduction.

The match detect 104 determines 412 if the final output indicates a match with the channel associated with the match detect 104. A final output of zero (00) indicates a match while a one (01) or a two (10) indicates a non-match. Including the channel number associated with the address (the start address or the upper address) as an input in the reduction process allows the match detect 104 to make a match determination from the final bit output of the reduction process.

FIG. 6 shows an example adjustment process 600 that the remap 106 may use to adjust the start address and the count if the match detect 104 determines that only part of the region lies within its associated channel (see FIG. 2).

In the adjustment process 600, the remap 106 calculates 602 a boundary address representing an address an interleaved amount beyond the start address. The interleaved amount is typically included in the address that includes the start address (see, e.g., the address 502 in FIG. 5), and in this example equals one hundred twenty-eight bytes. The remap 106 may calculate the boundary address by performing a logical AND operation on the start address and 0×FFFFFF80 and adding 0×80 (the interleaved amount).

The remap 106 also calculates 604 a lower count representing a number of bytes between the start address and the boundary address. The remap 106 may calculate the lower count by subtracting the start address from the boundary address.

The remap 106 also calculates 606 an upper count representing a number of bytes between the boundary address and a stop address (the start address plus the count). The remap 106 may calculate the upper count by subtracting the boundary address from the stop address and adding one (the one accounts for the fact that the lower count includes the boundary address).

If the channel associated with the remap 106 owns a lower part of the transfer (e.g., as determined through the determination process 300), then the remap 106 considers 608 the adjusted start address as the start address and the adjusted count as the lower count. If not (i.e., if the channel associated with the remap 106 owns an upper part of the transfer), then the remap 106 considers 610 the adjusted start address as the boundary address and the adjusted count as the upper count.

FIG. 7 shows an example remapping process 700 that the remap 106 may use to index an address within a channel. The remap 106 finds 702 a longest string of consecutive address bits with a value of one in the address to be indexed. The remap 106 may begin searching for the longest string with the least significant bit in the address. Once found, the remap 106 drops 704 the longest string from the address, right justifies 706 the remaining bits in the address. If the channel includes a power of two number of memory locations (e.g., addresses), then the remap 106 fills 708 the vacated bit positions (the most significant bits) with ones. This filling essentially adds three quarters to the remaining space of channels, e.g., starts the filling three quarters over from the address. The resulting bits form the remapped address.

If the channel is of a non-power of two, then a shifting of three quarters is not typically the same size as for a power of two channels (e.g., may not be two bit positions but some other number). The remap 106 determines 710 where to start adding ones in the vacated positions. The remap 106 may make such a determination by consulting one or more lookup tables including constants that indicate start addresses where the remap 106 may start filling 712 in ones. Each of the tables may be included in the remap 106 or be otherwise accessible to the remap 106 and may include constants for any number of channels and for any number of shifted bits. The resulting bits form the remapped address.

For example, in a three channel system, the lookup tables may be as follows, where the constant values are shown in hexadecimal format and where K0 represents three quarters of a channel, K1 represents three quarters plus three quarters of a channel K2 represents three quarters plus three quarters plus three quarters of a channel, etc. The tables show constant values up to 768 MBytes, but the values in the table may be scaled as appropriate for a larger number of MBytes.

MBytes

32

64

96

128

160

192

224

256

K11

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

K10

N/A

N/A

N/A

N/A

13FFFF

17FFFF

1BFFFF

1FFFFF

K9

N/A

7FFFF

BFFFF

FFFFF

13FFFE

17FFFE

1BFFFE

1FFFFE

K8

3FFFF

7FFFE

BFFFD

FFFFC

13FFFB

17FFFA

1BFFF9

1FFFF8

K7

3FFFC

7FFF8

BFFF4

FFFF0

13FFEC

17FFE8

1BFFE4

1FFFE0

K6

3FFF0

7FFE0

BFFD0

FFFC0

13FFB0

17FFA0

1BFF90

1FFF80

K5

3FFC0

7FF80

BFF40

FFF00

13FEC0

17FE80

1BFE40

1FFE00

K4

3FF00

7FE00

BFD00

FFC00

13FB00

17FA00

1BF900

1FF800

K3

3FC00

7F800

BF400

FF000

13EC00

17E800

1BE400

1FE000

K2

3F000

7E000

BD000

FC000

13B000

17A000

1BE9000

1F8000

K1

3C000

78000

B4000

F0000

12C000

168000

1A4000

1E000

K0

30000

60000

9000

C0000

F0000

120000

150000

180000

MBytes

288

320

352

384

416

448

480

512

K11

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

K10

23FFFF

27FFFF

2BFFFF

2FFFFF

33FFFF

37FFFF

3BFFFF

3FFFFF

K9

23FFFD

27FFFD

2BFFFD

2FFFFD

33FFFC

37FFFC

3BFFFC

3FFFFC

K8

23FFF7

27FFF6

2BFFF6

2FFFF4

33FFF3

37FFF2

3BFFF1

3FFFF0

K7

23FFDC

27FFD8

2BFFD4

2FFFD0

33FFCC

37FFC8

3BFFC4

3FFFC0

K6

23FF70

27FF60

2BFF50

2FFF40

33FF30

37FF20

3BFF10

3FFF00

K5

23FDC0

27FD80

2BFD40

2FFD00

33FCC0

37FC80

3BFC40

3FFC00

K4

23F700

27F600

2BF500

2FF400

33F300

37F200

3BF100

3FF000

K3

23DC00

27D800

2BD400

2FD000

33CC00

37C800

3BC400

3FC000

K2

237000

276000

2B5000

2F4000

333000

372000

3B1000

3F0000

K1

21C000

258000

294000

2D0000

30C000

348000

384000

3C0000

K0

1B0000

1E0000

210000

240000

270000

2A0000

2D0000

300000

MBytes

544

576

608

640

672

704

736

768

K11

43FFFF

47FFFF

4BFFFF

4FFFFF

53FFFF

57FFFF

5BFFFF

5FFFFF

K10

43FFFE

47FFFE

4BFFFE

4FFFFE

53FFFE

57FFFE

5BFFFE

5FFFFE

K9

43FFFB

47FFFB

4BFFFB

4FFFFB

53FFFA

57FFFA

5BFFFA

5FFFFA

K8

43FFEF

47FFEE

4BFFED

4FFFEC

53FFEB

57FFEA

5BFFE9

5FFFE8

K7

43FFBC

47FFB8

4BFFB4

4FFF80

53FFAC

57FFA8

5BFFA4

5FFFA0

K6

43FEF0

47FEE0

4BFED0

4FFEC0

53FEB0

57FEA0

5BFE90

5FFE80

K5

43FBCO

47FB80

4BFB40

4FFB00

53FAC0

57FA80

5BFA40

5FFA00

K4

43EF00

47EE00

4BED00

4FEC00

53EB00

57EA00

5BE900

5FE800

K3

43BC00

47B800

4BB400

4FB000

53AC00

57A800

5BA400

5FA000

K2

43BC00

47B800

4BB400

4FB000

53AC00

57A800

5BA400

5FA000

K1

3FC000

438000

474000

4B0000

4EC000

528000

564000

5A0000

K0

330000

360000

390000

3C0000

3F0000

420000

450000

480000

The remap 106 indexes all available addresses, e.g., all addresses handled by the channel control system 100 (see FIG. 1). As a simple example, in a system including three channels with eight addresses each and twenty-four addresses, address locations in the channels would be remapped as shown:

Index in

Channel

Channel 0

Channel 1

Channel 2

0

0

1

2

1

6

4

5

2

9

10

8

3

12

13

14

4

18

16

17

5

21

22

20

6

3

7

11

7

15

19

23

Although the processes in FIGS. 2, 3, 4, 6, and 7 are each described with reference to the elements included in the example channel control system 100 of FIG. 1, these or similar processes, each including the same, more, or fewer elements, reorganized or not, may be performed in the channel control system 100 or in another, similar system. Additionally, the processes in FIGS. 2, 3, 4, 6, and 7 are described systems using 128-byte interleaving and including three channels and thirty-one bit addresses, but the processes may be used (with any appropriate modifications) for any size interleaving, for any number of channels, and for addresses of any size. Furthermore, the processes in FIGS. 2, 3, 4, 6, and 7 need not all be performed together in the same system but may find applicability alone or in partial combination with two or more of the other processes.

Referring to FIG. 8, a machine 800 includes a processing system 802 including a memory controller 804 that may include or be configured similar to the channel control system 100 (see FIG. 100). The elements described with reference to FIG. 8 can be implemented in a variety of ways.

A consuming device 806 may need information stored at a location in a main memory 808. The consuming device 806 typically connects to the machine 800 via input/output (I/O) ports, bays, and/or slots 810 and requests data from the main memory 808 through a chipset 812 and a processor 814.

The memory controller 804 may control access to and map addresses in the main memory 808 as described above, interleaving reads/writes using multiple memory channels. The main memory 808 can include any memory mechanism capable of storing data. Examples of the main memory 808 include random access memory (RAM) such as dynamic RAM or static RAM, read only memory (ROM), flash memory, tapes, disks, buffers, and other types of similar storage mechanisms. The main memory 808 may include one storage mechanism, e.g., one RAM chip, or any combination of storage mechanisms, e.g., multiple RAM chips. For example, memory may include SDRAM. SDRAM generally refers to a type of DRAM that can run at much higher clock speeds than conventional memory. SDRAM can synchronize itself with a bus associated with a processor included in the computing system (e.g., the processor 814). DDR-SDRAM generally refers to a type of SDRAM that supports data transfers on both edges of each clock cycle (the rising and falling edges), effectively doubling the memory's data throughput.

The machine 800 can include any mechanism or device capable of processing data. Examples of the machine 800 include workstations, stationary personal computers, mobile personal computers, servers, personal digital assistants, pagers, telephones, and other similar mechanisms and devices.

The consuming device 806 can include an I/O device, network interface, or other mechanism that may communicate with or be included in the machine 800. I/O devices generally include devices used to transfer data into and/or out of a computer system. Examples of I/O devices include mice, keyboards, printers, display devices such as monitors, disk drives, graphics devices, joysticks, paddles, zip drives, scanners, CD drives, DVD drives, modems, cameras, video devices, microphones, and other similar types of internal, external, and internal/external devices. One consuming device is shown but the machine 800 may communicate with more than consuming device.

The I/O ports, bays, and/or slots 810 may include any mechanisms or interfaces capable of connecting one or more consuming devices to the machine 800. For example, the I/O ports, bays, and/or slots 810 may include peripheral component interconnect (PCI) slots, parallel ports, serial bus ports, disk drive bays, and other similar types of mechanisms and interfaces.

The processor 814 can include any processing mechanism such as a microprocessor or a central processing unit (CPU). The processor 814 may include one or more individual processors. The processor 814 may include a network processor, a general purpose embedded processor, or other similar type of processor.

The chipset 812 can include any number of chips/integrated circuits that can provide interfaces between the machine's subsystems.

Instructions and data are typically communicated to and from the main memory 808 in blocks. A block generally refers to a collection of bits or bytes communicated or processed as a group. A block may include any number of words, and a word may include any number of bits or bytes.

Data can be communicated between elements on communication links. The communication links can include any kind and any combination of communication links such as buses (of any type and size), physical ports, wireless links, and other similar links. For bus communication links, the buses can have any width, e.g., sixteen bits, thirty-two bits, sixty-four bits, etc, and may run at any speed, e.g., thirty-three Mega Hertz (MHz), 100 MHz, etc. A bus may have a sideband feature in which the bus includes parallel channels that can each simultaneously carry data and/or address information. Additionally, each of the communication links may include one or more individual communication links.

The memory controller 804 generally includes any mechanism capable of communicating with and managing the main memory 808. The memory controller 804 may include one or more chips and may be included in the chipset 812 or may be a mechanism independent from the chipset 812. The memory controller 804 may include any number of and any type of instructions, routines, applications, and/or programs.

Furthermore, the machine 800 is simplified for ease of explanation. The machine 800 may include more or fewer additional elements such as communication links, processors, storage mechanisms (buffers, caches, memories, databases, etc.), display mechanisms, consuming devices, bridges, chips, and other similar types of machine elements.

The techniques described here are not limited to any particular hardware or software configuration; they may find applicability in any computing or processing environment. The techniques may be implemented in hardware, software, or a combination of the two. The techniques may be implemented in programs executing on programmable machines such as mobile computers, stationary computers, personal digital assistants, and similar devices that each include a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and one or more output devices. Program code is applied to data entered using the input device to perform the functions described and to generate output information. The output information is applied to one or more output devices.

Each program may be implemented in a high level procedural or object oriented programming language to communicate with a machine system. However, the programs can be implemented in assembly or machine language, if desired. In any case, the language may be a compiled or interpreted language.

Each such program may be stored on a storage medium or device, e.g., compact disc read only memory (CD-ROM), hard disk, magnetic diskette, or similar medium or device, that is readable by a general or special purpose programmable machine for configuring and operating the machine when the storage medium or device is read by the computer to perform the procedures described in this document. The system may also be considered to be implemented as a machine-readable storage medium, configured with a program, where the storage medium so configured causes a machine to operate in a specific and predefined manner.

Other embodiments are within the scope of the following claims.

Claims (16)

1. A method comprising:

receiving an address corresponding to a memory having a non power of two number, X, of associated channels to the memory;

determining one or more of the channels to use in accessing the memory, the determining comprising applying a modulo-X based reduction to the address; and

indexing the address for a determined channel;

wherein the receiving comprises receiving a first address and a count, the method further comprising calculating a second address from the first address and the count, and the determining comprises applying the modulo-X based reduction to the first and second addresses to map the first and second addresses to the channels, wherein a single one of the channels is determined to be used in accessing the memory in response to receiving the first address if both the first and second addresses map to the single one of the channels.

2. The method of claim 1, wherein the applying the modulo-X based reduction to the address comprises including a channel number as input to the modulo-X based reduction.

3. A method comprising:

receiving an address corresponding to a memory having a non power of two number, X, of associated channels to the memory;

determining one or more of the channels to use in accessing the memory, the determining comprising applying a modulo-X based reduction to the address; and

indexing the address for a determined channel;

wherein the indexing comprises:

determining a longest string of consecutive bits having a value of one in the address;

dropping the longest string from the address;

justifying remaining bits in the address; and

filling vacated bits in the address with ones to create a remapped address for the determined channel.

4. The method of claim 3, wherein the determined channel has a non power of two number of corresponding memory locations, and the filling comprises filling the vacated bits in the address based on one or more lookup tables including constants that indicate start addresses for address filling.

5. An apparatus comprising:

a non power of two number, X, of channels to a memory; and

a control device configured to receive an address corresponding to the memory and determine one or more of the channels to use in accessing the memory by applying a modulo-X based reduction to the address;

wherein the address comprises a first address, the control device configured to receive the first address and a count, calculate a second address from the first address and the count, and determine the one or more of the channels by applying the modulo-X based reduction to the first and second addresses to map the first and second addresses to the channels, wherein a single one of the channels is determined to be used in accessing the memory in response to receipt of the first address if both the first and second addresses map to the single one of the channels.

6. The apparatus of claim 5, wherein the applying the modulo-X based reduction to the address comprises including a channel number as input to the modulo-X based reduction.

7. An apparatus comprising:

a non power of two number, X, of channels to a memory; and

a control device configured to receive an address corresponding to the memory and determine one or more of the channels to use in accessing the memory by applying a modulo-X based reduction to the address, the control device configured to determine a longest string of consecutive bits having a value of one in the address, drop the longest string from the address, justify remaining bits in the address, and fill vacated bits in the address with ones to create a remapped address for the determined channel.

8. The apparatus of claim 7, wherein the determined channel has a non power of two number of corresponding memory locations, and the control device configured to fill the vacated bits in the address based on one or more lookup tables including constants that indicate start addresses for address filling.

9. An apparatus comprising:

a non power of two number, X, of channels to a memory; and

a control device configured to receive an address corresponding to the memory and determine one or more of the channels to use in accessing the memory by applying a modulo-X based reduction to the address;

wherein the control device comprises X channel controllers, each of the channel controllers configured to receive the address corresponding to the memory and determine whether an associated channel is to be used in accessing the memory by applying the modulo-X based reduction to the address; and

wherein the address comprises a first address, each of the channel controllers comprises a match detect mechanism and a count remapping mechanism, the match detect mechanism configured to receive the first address and a count, calculate a second address from the first address and the count, and determine whether the associated channel is to be used in accessing the memory by applying the modulo-X based reduction to the first and second addresses, and the count remapping mechanism configured to receive the first address and the count and to remap the count.

10. The apparatus of claim 9, the count remapping mechanism further configured to index a third address within the associated channel.

11. The apparatus of claim 10, the count remapping mechanism configured to determine a longest string of consecutive bits having a value of one in the third address, drop the longest string from the third address, justify remaining bits in the third address, and fill vacated bits in the third address with ones to create a remapped address within the associated channel.

12. The apparatus of claim 11, wherein the associated channel has a non power of two number of corresponding memory locations, and the count remapping mechanism configured to fill the vacated bits in the third address based on one or more lookup tables including constants that indicate start addresses for address filling.

13. A system comprising:

the apparatus of claim 5, 7 or 9; and

the memory comprising a read-write memory.

14. The system of claim 13, wherein the read-write memory comprises a random access memory.

15. The system of claim 13, further comprising multiple additional devices configured to access the read-write memory using the control device.